JP5508427B2 - Liquid crystal display - Google Patents

Description

The present invention relates to a liquid crystal display device. More specifically, the present invention relates to a liquid crystal display device suitable for an ECB (Electrically Controlled Birefringence) type liquid crystal display device.

A liquid crystal display device is usually a pair of polarizers, a liquid crystal display panel (liquid crystal cell) sandwiched between both polarizers, and a liquid crystal display panel and at least one of the pair of polarizers. Or a plurality of retardation plates. The liquid crystal display panel has a pair of substrates disposed to face each other and a liquid crystal layer sandwiched between the substrates.

As a liquid crystal display panel method, a TN (Twisted Nematic) method, an STN (Super Twisted Nematic) method, an ECB method, an IPS (In-Plane Switching) method, a VA (Vertical Alignment) method, an OCB (Optical Bending Method). Examples include a HAN (Hybrid Aligned Nematic) method, an ASM (Axial Symmetric Aligned Microcell) method, a halftone gray scale method, a domain division method, a display method using a ferroelectric liquid crystal or an anti-ferroelectric liquid crystal, and the like.

Regarding the ECB method, a technique using a liquid crystal film in which nematic liquid crystals are fixed in a hybrid alignment state is disclosed (for example, see Patent Documents 1 to 4).

JP 2007-316211 A JP 2008-129177 A JP 2008-309957 A JP 2009-42657 A

However, in the ECB type liquid crystal display devices described in Patent Documents 1 to 4, the gradation may be reversed in a wide viewing angle range when displaying near black.

The present invention has been made in view of the above-described present situation, and an object of the present invention is to provide a liquid crystal display device that exhibits excellent gradation inversion characteristics in a state where black is displayed.

The inventors of the present invention have made various studies on a liquid crystal display device that exhibits excellent gradation inversion characteristics in a state in which the vicinity of black is displayed, and excludes a liquid crystal layer and a retardation plate (first retardation plate) including a liquid crystal film. The phase difference in the thickness direction of the member between the pair of polarizers is 130 nm or more, and / or the phase difference of the liquid crystal display panel is 210 to 310 nm, and the average tilt of the nematic liquid crystal contained in the liquid crystal film The angle is 34 to 40 °, the in-plane retardation of the second retardation plate is 130 to 150 nm, and the Nz coefficient of the second retardation plate is 1.35 to 1.75. Thus, the inventors have found that the viewing angle region in which gradation inversion occurs when the vicinity of black is displayed can be narrowed, and have conceived that the above-mentioned problems can be solved brilliantly, thereby achieving the present invention.

That is, the present invention is a liquid crystal display device including a first polarizer, a second polarizer, a liquid crystal display panel, a first retardation plate, and a second retardation plate, wherein the second polarizer is the first polarizer. The liquid crystal display panel is disposed between the first polarizer and the second polarizer, and the first retardation plate and the second retardation plate are independent of each other. The liquid crystal display panel is provided between the first polarizer or the second polarizer and the liquid crystal display panel, and the liquid crystal display panel is sandwiched between the pair of substrates opposed to each other and the pair of substrates. The liquid crystal layer includes homogeneously aligned liquid crystal molecules, the first retardation plate includes a liquid crystal film, and the liquid crystal film fixes nematic liquid crystal in a hybrid aligned state. The liquid crystal layer formed by The liquid crystal display device (hereinafter referred to as “the phase difference in the thickness direction of a member between the first polarizer and the second polarizer” excluding the first retardation plate is 120 nm or more. Also referred to as “first liquid crystal display device of the present invention”.

If the specific phase difference is less than 120 nm, the gradation inversion may not be sufficiently suppressed when the vicinity of black is displayed.

The configuration of the first liquid crystal display device of the present invention is not particularly limited by other components as long as such components are essential.
A preferred embodiment of the first liquid crystal display device of the present invention will be described in detail below.

The upper limit of the specific phase difference is not particularly limited, but is preferably 330 nm. Normally, the gradation inversion characteristic reaches a peak up to this level.

The first polarizer, the first retardation plate, the liquid crystal display panel, the second retardation plate, and the second polarizer are arranged in this order, and the specific retardation is 120 nm or more and 300 nm or less. May be. As a result, even better gradation inversion characteristics can be exhibited in a state where the vicinity of black is displayed.

The liquid crystal display device further includes a transparent protective layer having a thickness direction retardation of 25 nm or more and 35 nm or less, the first polarizer, the transparent protective layer, the first retardation plate, the liquid crystal display panel, The second retardation plate and the second polarizer may be arranged in this order, and the specific retardation may be 150 nm or more and 330 nm or less. As a result, even better gradation inversion characteristics can be exhibited in a state where the vicinity of black is displayed.

The liquid crystal display device further includes a third retardation plate that is optically uniaxial in the thickness direction, and the first polarizer, the first retardation plate, the liquid crystal display panel, and the second retardation. The plate, the third retardation plate, and the second polarizer may be arranged in this order, and the specific retardation may be 140 nm or more and 250 nm or less. As a result, even better gradation inversion characteristics can be exhibited in a state where the vicinity of black is displayed without deteriorating the isocontrast characteristics.

The liquid crystal display device further includes a third retardation plate that is optically uniaxial in the thickness direction, and includes the first polarizer, the first retardation plate, the liquid crystal display panel, and the third retardation. The plate, the second retardation plate, and the second polarizer may be arranged in this order, and the specific retardation may be 130 nm or more and 290 nm or less. As a result, even better gradation inversion characteristics can be exhibited in a state where the vicinity of black is displayed without deteriorating the isocontrast characteristics.

The liquid crystal display device further includes a third retardation plate that is optically uniaxial in the thickness direction, and includes the first polarizer, the first retardation plate, the third retardation plate, and the liquid crystal display. The panel, the second retardation plate, and the second polarizer may be arranged in this order, and the specific retardation may be 130 nm or more and 290 nm or less. As a result, even better gradation inversion characteristics can be exhibited in a state where the vicinity of black is displayed without deteriorating the isocontrast characteristics.

The liquid crystal display device further includes a third retardation plate that is optically uniaxial in the thickness direction, and the first polarizer, the third retardation plate, the first retardation plate, and the liquid crystal display. The panel, the second retardation plate, and the second polarizer may be arranged in this order, and the specific retardation may be 140 nm or more and 250 nm or less. As a result, even better gradation inversion characteristics can be exhibited in a state where the vicinity of black is displayed without deteriorating the isocontrast characteristics.

As described above, the first polarizer, the first retardation plate, the liquid crystal display panel, the second retardation plate, and the second polarizer are arranged in this order (hereinafter referred to as “first configuration”). The specific phase difference is preferably 150 nm or more and 250 nm or less. Thereby, in the first embodiment, it is possible to more surely show a more excellent gradation inversion characteristic in a state where the vicinity of black is displayed.

The first polarizer, the second retardation plate, the first retardation plate, the liquid crystal display panel, and the second polarizer are arranged in this order, and the specific retardation is 120 nm or more and 260 nm or less. May be. As a result, even better gradation inversion characteristics can be exhibited in a state where the vicinity of black is displayed.

The liquid crystal display device further includes a transparent protective layer having a thickness direction retardation of 25 nm or more and 35 nm or less, the first polarizer, the transparent protective layer, the second retardation plate, and the first retardation plate. The liquid crystal display panel and the second polarizer may be arranged in this order, and the specific phase difference may be not less than 150 nm and not more than 240 nm. As a result, even better gradation inversion characteristics can be exhibited in a state where the vicinity of black is displayed.

The liquid crystal display device further includes a third retardation plate that is optically uniaxial in the thickness direction, and includes the first polarizer, the second retardation plate, the first retardation plate, and the liquid crystal display. The panel, the third retardation plate, and the second polarizer may be arranged in this order, and the specific retardation may be 140 nm or more and 250 nm or less. As a result, even better gradation inversion characteristics can be exhibited in a state where the vicinity of black is displayed without deteriorating the isocontrast characteristics.

The liquid crystal display device further includes a third retardation plate that is optically uniaxial in the thickness direction, and includes the first polarizer, the second retardation plate, the first retardation plate, and the third retardation plate. The retardation plate, the liquid crystal display panel, and the second polarizer may be arranged in this order, and the specific retardation may be 140 nm or more and 210 nm or less. As a result, even better gradation inversion characteristics can be exhibited in a state where the vicinity of black is displayed without deteriorating the isocontrast characteristics.

The liquid crystal display device further includes a third retardation plate that is optically uniaxial in the thickness direction, and includes the first polarizer, the second retardation plate, the third retardation plate, and the first retardation plate. The retardation plate, the liquid crystal display panel, and the second polarizer may be arranged in this order, and the specific retardation may be 130 nm or more and 210 nm or less. As a result, even better gradation inversion characteristics can be exhibited in a state where the vicinity of black is displayed without deteriorating the isocontrast characteristics.

The liquid crystal display device further includes a third retardation plate that is optically uniaxial in the thickness direction, and includes the first polarizer, the third retardation plate, the second retardation plate, and the first retardation plate. The retardation plate, the liquid crystal display panel, and the second polarizer may be arranged in this order, and the specific retardation may be 140 nm or more and 270 nm or less. As a result, even better gradation inversion characteristics can be exhibited in a state where the vicinity of black is displayed without deteriorating the isocontrast characteristics.

As described above, the first polarizer, the second retardation plate, the first retardation plate, the liquid crystal display panel, and the second polarizer are arranged in this order (hereinafter referred to as “second configuration”). The specific phase difference is preferably 150 nm or more and 210 nm or less. Thereby, in the second embodiment, it is possible to show further excellent gradation inversion characteristics in a state where the vicinity of black is displayed.

According to the first liquid crystal display device of the present invention, it is possible to achieve a non-gradation inversion occupancy of 60% or more.

The present invention is also a liquid crystal display device including a first polarizer, a second polarizer, a liquid crystal display panel, a first retardation plate, and a second retardation plate, wherein the second polarizer is the first polarization. The liquid crystal display panel is disposed between the first polarizer and the second polarizer, and the first retardation plate is disposed between the first polarizer and the liquid crystal display panel. And the second retardation plate is provided between the second polarizer and the liquid crystal display panel, and the liquid crystal display panel is narrowed between a pair of substrates disposed opposite to each other and the pair of substrates. The liquid crystal layer includes homogeneously aligned liquid crystal molecules, the liquid crystal display panel has a retardation of 210 to 310 nm, and the first retardation plate includes a liquid crystal film. The liquid crystal film hybridizes nematic liquid crystal. The nematic liquid crystal is formed by fixing in an aligned state, the average tilt angle of the nematic liquid crystal is 34 to 40 °, the in-plane retardation of the second retardation plate is 130 to 150 nm, The Nz coefficient of the two phase difference plate is also a liquid crystal display device (hereinafter also referred to as “second liquid crystal display device of the present invention”) of 1.35 to 1.75.

The configuration of the second liquid crystal display device of the present invention is not particularly limited by other components as long as such components are essential.

According to the second liquid crystal display device of the present invention, preferably, a non-gradation inversion occupancy ratio of 60% or more can be achieved.

According to the first and second liquid crystal display devices of the present invention, excellent gradation inversion characteristics can be exhibited in a state where the vicinity of black is displayed.

1 is a schematic cross-sectional view illustrating a configuration of a liquid crystal display device according to Embodiment 1. FIG. 1 is a schematic cross-sectional view illustrating a configuration of a liquid crystal display device according to Embodiment 1. FIG. 1 is a schematic cross-sectional view illustrating a configuration of a liquid crystal display device according to Embodiment 1. FIG. 1 is a schematic cross-sectional view illustrating a configuration of a liquid crystal display device according to Embodiment 1. FIG. 1 is a schematic cross-sectional view illustrating a configuration of a liquid crystal display device according to Embodiment 1. FIG. It is a perspective schematic diagram of the nematic liquid crystal which concerns on Embodiment 1 for demonstrating a tilt angle and a twist angle. It is a cross-sectional schematic diagram of the liquid-crystal layer which concerns on Embodiment 1 for demonstrating the orientation direction of homogeneous liquid crystal. 1 is a schematic cross-sectional view illustrating a configuration 1 of a liquid crystal display device according to Embodiment 1. FIG. FIG. 3 is a schematic cross-sectional view showing the configuration 1 + transparent protective layer of the liquid crystal display device according to the first embodiment. 1 is a schematic cross-sectional view illustrating a configuration 1-1 of a liquid crystal display device according to Embodiment 1. FIG. FIG. 3 is a schematic cross-sectional view illustrating a configuration 1-2 of the liquid crystal display device according to the first embodiment. 3 is a schematic cross-sectional view illustrating a configuration 1-3 of a liquid crystal display device according to Embodiment 1. FIG. 4 is a schematic cross-sectional view illustrating a configuration 1-4 of the liquid crystal display device according to Embodiment 1. FIG. FIG. 3 is a schematic cross-sectional view illustrating a configuration 2 of the liquid crystal display device according to the first embodiment. FIG. 3 is a schematic cross-sectional view illustrating a configuration 2 + a transparent protective layer of the liquid crystal display device according to the first embodiment. 3 is a schematic cross-sectional view showing a configuration 2-1 of the liquid crystal display device according to Embodiment 1. FIG. 4 is a schematic cross-sectional view illustrating a configuration 2-2 of the liquid crystal display device according to Embodiment 1. FIG. FIG. 3 is a schematic cross-sectional view illustrating a configuration 2-3 of the liquid crystal display device according to the first embodiment. 4 is a schematic cross-sectional view illustrating a configuration 2-4 of the liquid crystal display device according to Embodiment 1. FIG. FIG. 3 is a conceptual diagram for explaining an arrangement form of optical axes of the optical member according to the first embodiment. 5 is a graph showing the gradation inversion characteristics of the configuration 1 of the liquid crystal display device according to the first embodiment, where (a) shows a case where the total Rth = 70 nm, (b) shows a case where the total Rth = 126 nm, and (c) shows In the case of total Rth = 154 nm, (d) shows the case of total Rth = 182 nm. 6 is a graph showing the gradation inversion characteristics of the configuration 1 of the liquid crystal display device according to the first embodiment, where (e) is a total Rth = 210 nm, (f) is a total Rth = 252 nm, and (g) is a graph. The total Rth = 294 nm is shown. 6 is a graph showing gradation inversion characteristics of Configuration 2 of the liquid crystal display device according to the first embodiment, where (a) shows a case where total Rth = 70 nm, (b) shows a case where total Rth = 126 nm, and (c) shows In the case of total Rth = 154 nm, (d) shows the case of total Rth = 182 nm. 5 is a graph showing gradation inversion characteristics of Configuration 2 of the liquid crystal display device according to the first embodiment, where (e) is for the total Rth = 210 nm, (f) is for the total Rth = 252 nm, and (g) is The total Rth = 294 nm is shown. 5 is a graph showing isocontrast characteristics of the configuration 1 of the liquid crystal display device according to Embodiment 1, where (a) shows a case where total Rth = 70 nm, (b) shows a case where total Rth = 126 nm, and (c) shows a case where In the case of total Rth = 154 nm, (d) shows the case of total Rth = 182 nm. 4 is a graph showing isocontrast characteristics of the configuration 1 of the liquid crystal display device according to the first embodiment, where (e) is a total Rth = 210 nm, (f) is a total Rth = 252 nm, and (g) is The total Rth = 294 nm is shown. 4 is a graph showing isocontrast characteristics of the configuration 2 of the liquid crystal display device according to the first embodiment, where (a) shows a total Rth = 70 nm, (b) shows a total Rth = 126 nm, and (c) shows In the case of total Rth = 154 nm, (d) shows the case of total Rth = 182 nm. 4 is a graph showing isocontrast characteristics of the configuration 2 of the liquid crystal display device according to the first embodiment, where (e) is a total Rth = 210 nm, (f) is a total Rth = 252 nm, and (g) is The total Rth = 294 nm is shown. 4 is a graph showing non-gradation inversion occupancy rates of configurations 1 and 2 of the liquid crystal display device according to the first embodiment. 4 is a graph showing gradation inversion characteristics of the liquid crystal display device according to the first embodiment 1 + transparent protective layer, where (a) shows a total Rth = 100 nm, (b) shows a total Rth = 156 nm; c) shows the case where total Rth = 184 nm, and (d) shows the case where total Rth = 212 nm. 6 is a graph showing gradation inversion characteristics of the liquid crystal display device according to the first embodiment 1 + transparent protective layer, where (e) is a total Rth = 240 nm, and (f) is a total Rth = 282 nm. g) shows the case where total Rth = 324 nm. 4 is a graph showing the gradation inversion characteristics of the configuration 2 + transparent protective layer of the liquid crystal display device according to the first embodiment, where (a) shows a total Rth = 100 nm, (b) shows a total Rth = 156 nm; c) shows the case where total Rth = 184 nm, and (d) shows the case where total Rth = 212 nm. 4 is a graph showing the gradation inversion characteristics of the configuration 2 + transparent protective layer of the liquid crystal display device according to the first embodiment, where (e) shows a case where total Rth = 240 nm, and (f) shows a case where total Rth = 282 nm. g) shows the case where total Rth = 324 nm. 6 is a graph showing the isocontrast characteristics of the liquid crystal display device according to the first embodiment 1 + transparent protective layer, where (a) shows a total Rth = 100 nm, (b) shows a total Rth = 156 nm, (c ) Shows the case of total Rth = 184 nm, and (d) shows the case of total Rth = 212 nm. 4 is a graph showing the isocontrast characteristics of the liquid crystal display device according to the first exemplary embodiment 1 + transparent protective layer, where (e) is a total Rth = 240 nm, (f) is a total Rth = 282 nm, (g ) Shows the case where the total Rth = 324 nm. 5 is a graph showing isocontrast characteristics of the configuration 2 + transparent protective layer of the liquid crystal display device according to the first embodiment, where (a) is a total Rth = 100 nm, (b) is a total Rth = 156 nm, (c ) Shows the case of total Rth = 184 nm, and (d) shows the case of total Rth = 212 nm. 6 is a graph showing isocontrast characteristics of the configuration 2 + transparent protective layer of the liquid crystal display device according to the first embodiment, where (e) is a total Rth = 240 nm, (f) is a total Rth = 282 nm, (g ) Shows the case where the total Rth = 324 nm. 4 is a graph showing the non-gradation inversion occupancy ratio of the configuration 1 + transparent protective layer and the configuration 2 + transparent protective layer of the liquid crystal display device according to the first embodiment. 4 is a graph showing gradation inversion characteristics of the configuration 1-1 of the liquid crystal display device according to the first embodiment, where (a) shows a case where the total Rth = 70 nm, and (b) shows a case where the total Rth = 130 nm. ) Shows the case where the total Rth = 140 nm, and (d) shows the case where the total Rth = 150 nm. 6 is a graph showing the gradation inversion characteristics of the configuration 1-1 of the liquid crystal display device according to the first embodiment, where (e) is a total Rth = 160 nm, (f) is a total Rth = 170 nm, (g ) Shows the case where total Rth = 190 nm, and (h) shows the case where total Rth = 210 nm. 4 is a graph showing gradation inversion characteristics of the configuration 1-1 of the liquid crystal display device according to the first embodiment, where (i) is a total Rth = 230 nm, (j) is a total Rth = 250 nm, (k ) Shows the case of total Rth = 270 nm, and (l) shows the case of total Rth = 290 nm. 4 is a graph showing the gradation inversion characteristics of the configuration 1-2 of the liquid crystal display device according to the first embodiment, where (a) shows a case where the total Rth = 70 nm, (b) shows a case where the total Rth = 130 nm; ) Shows the case where the total Rth = 140 nm, and (d) shows the case where the total Rth = 150 nm. 6 is a graph showing the gradation inversion characteristics of the configuration 1-2 of the liquid crystal display device according to the first embodiment, where (e) shows a case where the total Rth = 160 nm, and (f) shows a case where the total Rth = 170 nm. ) Shows the case where total Rth = 190 nm, and (h) shows the case where total Rth = 210 nm. 6 is a graph showing gradation inversion characteristics of the configuration 1-2 of the liquid crystal display device according to the first embodiment, where (i) is a total Rth = 230 nm, (j) is a total Rth = 250 nm, (k ) Shows the case of total Rth = 270 nm, and (l) shows the case of total Rth = 290 nm. 4 is a graph showing gradation inversion characteristics of the configuration 1-3 of the liquid crystal display device according to the first embodiment, where (a) shows a case where the total Rth = 70 nm, and (b) shows a case where the total Rth = 130 nm. ) Shows the case where the total Rth = 140 nm, and (d) shows the case where the total Rth = 150 nm. 4 is a graph showing the gradation inversion characteristics of the configuration 1-3 of the liquid crystal display device according to the first embodiment, where (e) is a total Rth = 160 nm, (f) is a total Rth = 170 nm, (g ) Shows the case where total Rth = 190 nm, and (h) shows the case where total Rth = 210 nm. 4 is a graph showing gradation inversion characteristics of the configuration 1-3 of the liquid crystal display device according to the first embodiment, where (i) is a total Rth = 230 nm, (j) is a total Rth = 250 nm, (k ) Shows the case of total Rth = 270 nm, and (l) shows the case of total Rth = 290 nm. 5 is a graph showing gradation inversion characteristics of the configuration 1-4 of the liquid crystal display device according to the first embodiment, where (a) shows a case where the total Rth = 70 nm, and (b) shows a case where the total Rth = 130 nm. ) Shows the case where the total Rth = 140 nm, and (d) shows the case where the total Rth = 150 nm. 4 is a graph showing gradation inversion characteristics of the configuration 1-4 of the liquid crystal display device according to the first embodiment, where (e) shows a case where the total Rth = 160 nm and (f) shows a case where the total Rth = 170 nm (g ) Shows the case where total Rth = 190 nm, and (h) shows the case where total Rth = 210 nm. 4 is a graph showing gradation inversion characteristics of the configuration 1-4 of the liquid crystal display device according to the first embodiment, where (i) is a total Rth = 230 nm, (j) is a total Rth = 250 nm, (k ) Shows the case of total Rth = 270 nm, and (l) shows the case of total Rth = 290 nm. 4 is a graph showing isocontrast characteristics of the configuration 1-1 of the liquid crystal display device according to the first embodiment, where (a) shows a case where the total Rth = 70 nm and (b) shows a case where the total Rth = 130 nm. (D) shows the case where total Rth = 140 nm, and (d) shows the case where total Rth = 150 nm. 4 is a graph showing isocontrast characteristics of the configuration 1-1 of the liquid crystal display device according to the first embodiment, where (e) is for the total Rth = 160 nm, and (f) is for the total Rth = 170 nm. In the case of total Rth = 190 nm, (h) shows the case of total Rth = 210 nm. 6 is a graph showing isocontrast characteristics of the configuration 1-1 of the liquid crystal display device according to the first embodiment, where (i) is a total Rth = 230 nm, (j) is a total Rth = 250 nm, and (k). Represents the case where total Rth = 270 nm, and (l) represents the case where total Rth = 290 nm. 4 is a graph showing isocontrast characteristics of Configuration 1-2 of the liquid crystal display device according to Embodiment 1, where (a) shows a case where total Rth = 70 nm and (b) shows a case where total Rth = 130 nm. (D) shows the case where total Rth = 140 nm, and (d) shows the case where total Rth = 150 nm. 4 is a graph showing isocontrast characteristics of the configuration 1-2 of the liquid crystal display device according to the first embodiment, where (e) is a total Rth = 160 nm and (f) is a total Rth = 170 nm. In the case of total Rth = 190 nm, (h) shows the case of total Rth = 210 nm. 6 is a graph showing isocontrast characteristics of the configuration 1-2 of the liquid crystal display device according to the first embodiment, where (i) is a total Rth = 230 nm, (j) is a total Rth = 250 nm, and (k). Represents the case where total Rth = 270 nm, and (l) represents the case where total Rth = 290 nm. 4 is a graph showing isocontrast characteristics of Configuration 1-3 of the liquid crystal display device according to Embodiment 1, where (a) shows a case where total Rth = 70 nm, (b) shows a case where total Rth = 130 nm, (c) (D) shows the case where total Rth = 140 nm, and (d) shows the case where total Rth = 150 nm. 4 is a graph showing isocontrast characteristics of Configuration 1-3 of the liquid crystal display device according to Embodiment 1, wherein (e) is for the case of total Rth = 160 nm, and (f) is for the case of total Rth = 170 nm. In the case of total Rth = 190 nm, (h) shows the case of total Rth = 210 nm. 4 is a graph showing isocontrast characteristics of the configuration 1-3 of the liquid crystal display device according to the first embodiment, where (i) is a total Rth = 230 nm, (j) is a total Rth = 250 nm, and (k). Represents the case where total Rth = 270 nm, and (l) represents the case where total Rth = 290 nm. 4 is a graph showing isocontrast characteristics of the configuration 1-4 of the liquid crystal display device according to the first embodiment, where (a) shows a case where the total Rth = 70 nm, and (b) shows a case where the total Rth = 130 nm. (D) shows the case where total Rth = 140 nm, and (d) shows the case where total Rth = 150 nm. 4 is a graph showing isocontrast characteristics of the configuration 1-4 of the liquid crystal display device according to the first embodiment, where (e) is for the total Rth = 160 nm and (f) is for the total Rth = 170 nm. In the case of total Rth = 190 nm, (h) shows the case of total Rth = 210 nm. 4 is a graph showing isocontrast characteristics of the configuration 1-4 of the liquid crystal display device according to the first embodiment, where (i) is a total Rth = 230 nm, (j) is a total Rth = 250 nm, and (k). Represents the case where total Rth = 270 nm, and (l) represents the case where total Rth = 290 nm. 6 is a graph showing a non-gradation inversion occupancy ratio and a viewing angle occupancy ratio of the configuration 1-1 of the liquid crystal display device according to the first embodiment. 6 is a graph showing a non-gradation inversion occupancy ratio and a viewing angle occupancy ratio of the configuration 1-2 of the liquid crystal display device according to the first embodiment. 4 is a graph showing a non-grayscale inversion occupancy and a viewing angle occupancy of the configuration 1-3 of the liquid crystal display device according to the first embodiment. 4 is a graph showing a non-gradation inversion occupancy and a viewing angle occupancy of a configuration 1-4 of the liquid crystal display device according to the first embodiment. 6 is a graph showing non-gradation inversion occupancy and viewing angle occupancy of configurations 1-1 to 1-4 of the liquid crystal display device according to the first embodiment. 6 is a graph showing gradation inversion characteristics of the configuration 2-1 of the liquid crystal display device according to the first embodiment, where (a) shows a case where the total Rth = 70 nm, and (b) shows a case where the total Rth = 130 nm. ) Shows the case where the total Rth = 140 nm, and (d) shows the case where the total Rth = 150 nm. 4 is a graph showing the gradation inversion characteristics of the configuration 2-1 of the liquid crystal display device according to the first embodiment, where (e) is a total Rth = 160 nm, (f) is a total Rth = 170 nm, (g ) Shows the case where total Rth = 190 nm, and (h) shows the case where total Rth = 210 nm. 4 is a graph showing gradation inversion characteristics of the configuration 2-1 of the liquid crystal display device according to the first embodiment, where (i) is a total Rth = 230 nm, (j) is a total Rth = 250 nm, (k ) Shows the case of total Rth = 270 nm, and (l) shows the case of total Rth = 290 nm. 4 is a graph showing gradation inversion characteristics of the configuration 2-2 of the liquid crystal display device according to the first embodiment, where (a) shows a case where the total Rth = 70 nm and (b) shows a case where the total Rth = 130 nm. ) Shows the case where the total Rth = 140 nm, and (d) shows the case where the total Rth = 150 nm. 6 is a graph showing the gradation inversion characteristics of the configuration 2-2 of the liquid crystal display device according to the first embodiment, where (e) is for the total Rth = 160 nm, (f) is for the total Rth = 170 nm, (g ) Shows the case where total Rth = 190 nm, and (h) shows the case where total Rth = 210 nm. 4 is a graph showing gradation inversion characteristics of the configuration 2-2 of the liquid crystal display device according to the first embodiment, where (i) is a total Rth = 230 nm, (j) is a total Rth = 250 nm, (k ) Shows the case of total Rth = 270 nm, and (l) shows the case of total Rth = 290 nm. 4 is a graph showing the gradation inversion characteristics of the configuration 2-3 of the liquid crystal display device according to the first embodiment, where (a) shows a case where the total Rth = 70 nm, and (b) shows a case where the total Rth = 130 nm. ) Shows the case where the total Rth = 140 nm, and (d) shows the case where the total Rth = 150 nm. 4 is a graph showing the gradation inversion characteristics of the configuration 2-3 of the liquid crystal display device according to the first embodiment, where (e) is for the total Rth = 160 nm, and (f) is for the total Rth = 170 nm (g ) Shows the case where total Rth = 190 nm, and (h) shows the case where total Rth = 210 nm. 6 is a graph showing gradation inversion characteristics of the configuration 2-3 of the liquid crystal display device according to the first embodiment, where (i) is a total Rth = 230 nm, (j) is a total Rth = 250 nm, (k ) Shows the case of total Rth = 270 nm, and (l) shows the case of total Rth = 290 nm. 4 is a graph showing gradation inversion characteristics of the configuration 2-4 of the liquid crystal display device according to the first embodiment. (A) shows a case where the total Rth = 70 nm, (b) shows a case where the total Rth = 130 nm, (c ) Shows the case where the total Rth = 140 nm, and (d) shows the case where the total Rth = 150 nm. 4 is a graph showing the gradation inversion characteristics of the configuration 2-4 of the liquid crystal display device according to the first embodiment, where (e) is for the total Rth = 160 nm, and (f) is for the total Rth = 170 nm (g ) Shows the case where total Rth = 190 nm, and (h) shows the case where total Rth = 210 nm. 4 is a graph showing the gradation inversion characteristics of the configuration 2-4 of the liquid crystal display device according to the first embodiment, where (i) is a total Rth = 230 nm, (j) is a total Rth = 250 nm, (k ) Shows the case of total Rth = 270 nm, and (l) shows the case of total Rth = 290 nm. 4 is a graph showing isocontrast characteristics of the configuration 2-1 of the liquid crystal display device according to Embodiment 1, where (a) shows a case where the total Rth = 70 nm and (b) shows a case where the total Rth = 130 nm. (D) shows the case where total Rth = 140 nm, and (d) shows the case where total Rth = 150 nm. 4 is a graph showing isocontrast characteristics of the configuration 2-1 of the liquid crystal display device according to the first embodiment, where (e) is for the total Rth = 160 nm and (f) is for the total Rth = 170 nm. In the case of total Rth = 190 nm, (h) shows the case of total Rth = 210 nm. 4 is a graph showing isocontrast characteristics of the configuration 2-1 of the liquid crystal display device according to the first embodiment, where (i) is a total Rth = 230 nm, (j) is a total Rth = 250 nm, and (k). Represents the case where total Rth = 270 nm, and (l) represents the case where total Rth = 290 nm. 4 is a graph showing isocontrast characteristics of the configuration 2-2 of the liquid crystal display device according to the first embodiment, where (a) shows a case where the total Rth = 70 nm, and (b) shows a case where the total Rth = 130 nm. (D) shows the case where total Rth = 140 nm, and (d) shows the case where total Rth = 150 nm. 5 is a graph showing isocontrast characteristics of the configuration 2-2 of the liquid crystal display device according to the first embodiment, where (e) is a total Rth = 160 nm and (f) is a total Rth = 170 nm. In the case of total Rth = 190 nm, (h) shows the case of total Rth = 210 nm. 4 is a graph showing isocontrast characteristics of the configuration 2-2 of the liquid crystal display device according to the first embodiment, where (i) is a total Rth = 230 nm, (j) is a total Rth = 250 nm, and (k). Represents the case where total Rth = 270 nm, and (l) represents the case where total Rth = 290 nm. 4 is a graph showing isocontrast characteristics of the configuration 2-3 of the liquid crystal display device according to Embodiment 1, wherein (a) shows a case where the total Rth = 70 nm, (b) shows a case where the total Rth = 130 nm, (c) (D) shows the case where total Rth = 140 nm, and (d) shows the case where total Rth = 150 nm. 4 is a graph showing isocontrast characteristics of the configuration 2-3 of the liquid crystal display device according to the first embodiment, where (e) is a total Rth = 160 nm and (f) is a total Rth = 170 nm. In the case of total Rth = 190 nm, (h) shows the case of total Rth = 210 nm. 4 is a graph showing isocontrast characteristics of the configuration 2-3 of the liquid crystal display device according to the first embodiment, where (i) is a total Rth = 230 nm, (j) is a total Rth = 250 nm, and (k). Represents the case where total Rth = 270 nm, and (l) represents the case where total Rth = 290 nm. 4 is a graph showing isocontrast characteristics of the configuration 2-4 of the liquid crystal display device according to the first embodiment, where (a) shows a case where the total Rth = 70 nm, and (b) shows a case where the total Rth = 130 nm. (D) shows the case where total Rth = 140 nm, and (d) shows the case where total Rth = 150 nm. 4 is a graph showing isocontrast characteristics of the configuration 2-4 of the liquid crystal display device according to the first embodiment, where (e) is for the total Rth = 160 nm and (f) is for the total Rth = 170 nm. In the case of total Rth = 190 nm, (h) shows the case of total Rth = 210 nm. 4 is a graph showing isocontrast characteristics of the configuration 2-4 of the liquid crystal display device according to the first embodiment, where (i) is a total Rth = 230 nm, (j) is a total Rth = 250 nm, and (k). Represents the case where total Rth = 270 nm, and (l) represents the case where total Rth = 290 nm. 4 is a graph showing a non-gradation inversion occupancy ratio and a viewing angle occupancy ratio of the configuration 2-1 of the liquid crystal display device according to the first embodiment. 4 is a graph showing a non-gradation inversion occupancy ratio and a viewing angle occupancy ratio of the configuration 2-2 of the liquid crystal display device according to the first embodiment. 6 is a graph showing a non-gradation inversion occupancy and a viewing angle occupancy of the configuration 2-3 of the liquid crystal display device according to the first embodiment. 4 is a graph showing a non-gradation inversion occupancy ratio and a viewing angle occupancy ratio in Configuration 2-4 of the liquid crystal display device according to Embodiment 1. 6 is a graph showing non-gradation inversion occupancy and viewing angle occupancy of configurations 2-1 to 2-4 of the liquid crystal display device according to the first embodiment. It is a graph which shows the non-grayscale inversion occupation rate and viewing angle occupation rate of the structure 1, the structure 1 + transparent protective layer, and the structures 1-1 to 1-4. It is a graph which shows the non-grayscale inversion occupation rate and viewing angle occupation rate of the structure 2, the structure 2+ transparent protective layer, and the structures 2-1 to 2-4. It is a cross-sectional schematic diagram which shows the structure of the liquid crystal display device which concerns on Examples 1-3. It is a cross-sectional schematic diagram which shows the structure of the liquid crystal display device which concerns on Examples 4-6. 6 is a graph showing non-gradation inversion occupancy rates of liquid crystal display devices according to Examples 1 to 6 and Comparative Example 1; The iso-contrast characteristics of a TN liquid crystal display device provided with a wide view film are shown. The gradation inversion characteristics of a TN liquid crystal display device provided with a wide view film are shown. An iso-contrast characteristic of an ECB type liquid crystal display device is shown. 2 shows gradation inversion characteristics of an ECB liquid crystal display device. An iso-contrast characteristic of an ECB type liquid crystal display device is shown. 2 shows gradation inversion characteristics of an ECB liquid crystal display device. The isocontrast characteristic of the structure 2 of the liquid crystal display device which concerns on Embodiment 1 is shown. 2 shows gradation inversion characteristics of Configuration 2 of the liquid crystal display device according to Embodiment 1. The isocontrast characteristic of the structure 1 of the liquid crystal display device which concerns on Embodiment 1 is shown. 2 shows gradation inversion characteristics of Configuration 1 of the liquid crystal display device according to Embodiment 1. The isocontrast characteristics of an ASV liquid crystal display device are shown. 2 shows gradation inversion characteristics of an ASV liquid crystal display device. The viewing angle dependence of the phase difference of an ECB liquid crystal display panel is shown. 6 is a schematic cross-sectional view illustrating a configuration of a liquid crystal display device according to Embodiment 2. FIG. 4 is a graph showing a relationship between a residual phase difference and an applied voltage in the liquid crystal display device according to Embodiment 1.

In the present specification, the non-gradation inversion occupancy is a percentage of a region where gradation inversion does not occur with respect to the entire viewing angle region. The presence or absence of gradation inversion is determined by comparing the luminance ratio between the 0 gradation and the 7 gradation in the 64 gradation display from the 0 gradation (black display) to the 63 gradation (white display). To do.

Further, in this specification, the viewing angle occupancy is a percentage of a region having a contrast ratio of 50: 1 or more with respect to the entire viewing angle region.

The all viewing angle region means a region having all directions and a polar angle of 0 to 80 °.

In the present specification, the liquid crystal film means a film obtained by forming a liquid crystal substance such as a low molecular liquid crystal or a polymer liquid crystal into a film. Although the presence or absence of liquid crystallinity of the liquid crystal film itself is not particularly limited, the liquid crystal film usually does not exhibit liquid crystallinity.

In the present specification, the average tilt angle means an average value of angles formed by a director of a nematic liquid crystal and a liquid crystal film plane in the thickness direction of the liquid crystal film. The average inclination angle can be obtained by applying a crystal rotation method.

In addition, the definitions of terms and symbols in the present specification are as follows unless otherwise specified.
(1) Main refractive index (nx, ny, nz)
“Nx” is the refractive index in the direction in which the refractive index is maximum within the plane of the optically anisotropic layer (that is, the slow axis direction), and “ny” is It is the refractive index in the orthogonal direction (that is, the fast axis direction), and “nz” is the refractive index in the thickness direction of the layer.
(2) In-plane phase difference Re
The in-plane retardation Re is a retardation value obtained by (nx−ny) × d, where d (nm) is the thickness of the optically anisotropic layer.
(3) Thickness direction retardation Rth
The retardation value Rth in the thickness direction is a retardation value obtained by ((nx + ny) / 2−nz) × d, where d (nm) is the thickness of the optically anisotropic layer.
(4) Nz coefficient The Nz coefficient is a value defined by (nx-nz) / (nx-ny).
(5) The Re, Rth, and Nz coefficients satisfy the relationship of Rth = Re × (Nz coefficient−0.5).

Moreover, the retardation value of the optically anisotropic layer was measured using Rets-200PT-Rf manufactured by Otsuka Electronics.

Further, the Nz coefficient of the optically anisotropic layer was measured using Rets-200PT-Rf manufactured by Otsuka Electronics Co., Ltd. Further, the Nz coefficient is a retardation value in the front direction (normal direction of the screen) and a retardation value from a direction rotated 45 ° from the normal direction with the slow axis of the optically anisotropic layer as the rotation axis. The calculation was made based on the refractive index of the optically anisotropic layer and the thickness of the optically anisotropic layer.

Further, EZcontrast manufactured by ELDIM was used for the measurement of gradation inversion characteristics.

In this specification, the refractive index, retardation value, and Nz coefficient are all values for monochromatic light at 25 ° C. and a wavelength of 550 nm unless otherwise specified.

Embodiments will be described below, and the present invention will be described in more detail with reference to the drawings. However, the present invention is not limited only to these embodiments.

(Embodiment 1)
The liquid crystal display device of the present embodiment is a transmissive liquid crystal display device. As shown in FIG. 1, the first polarizer 5, the liquid crystal display panel (liquid crystal cell) 10, the second polarizer 6, and the first phase difference A plate 11 and a second phase difference plate 12 and a backlight provided behind them are provided. The first polarizer 5, the liquid crystal display panel 10, and the second polarizer 6 are arranged in this order. The first retardation plate 11 and the second retardation plate 12 are disposed between the first polarizer 5 or the second polarizer 6 and the liquid crystal display panel 10. The first retardation plate 11 and the second retardation plate 12 may be arranged on the same polarizer side or may be arranged on different polarizer sides. When arranged on the same polarizer side, the first retardation plate 11 is usually arranged closer to the liquid crystal display panel 10 than the second retardation plate 12. In addition, usually no other optically anisotropic layer is provided between the first retardation plate 11 and the liquid crystal display panel.

The liquid crystal display device of the present embodiment further includes a third retardation plate as necessary. The third retardation plate is disposed between two adjacent members among the first polarizer 5, the liquid crystal display panel 10, the second polarizer 6, the first retardation plate 11, and the second retardation plate 12. .

As shown in FIG. 2, the liquid crystal display panel 10 includes a pair of transparent substrates 1 and 2 arranged to face each other, and a liquid crystal layer 3 is sandwiched between the substrates 1 and 2.

And the thickness (for example, the 2nd phase difference plate 12, the 3rd phase difference plate, etc.) which exists between the 1st polarizer 5 and the 2nd polarizer 6 except the liquid crystal layer 3 and the 1st phase difference plate 11 A specific phase difference (hereinafter, also referred to as “total Rth”) that is a phase difference between directions is 120 nm or more. Thereby, it is possible to exhibit excellent gradation inversion characteristics when displaying near black.

The upper limit of the total Rth is not particularly limited, but is usually about 330 nm. Normally, the gradation inversion characteristic reaches a peak up to this level.

Further, according to the liquid crystal display device of Embodiment 1, it is possible to achieve a non-gradation inversion occupancy rate of preferably 60% or more (more preferably 65% or more, and further preferably 70% or more). If the non-gradation inversion occupancy is less than 60%, it may be felt that gradation inversion is not sufficiently suppressed when the vicinity of black is displayed.

In addition, the thickness of each member is not specifically limited, You may set similarly to the case of a general liquid crystal display device.

The liquid crystal layer 3 is formed of a liquid crystal composition including various general low molecular liquid crystals, polymer liquid crystals, and the like, and as shown in FIG. 3, liquid crystal molecules 4 (hereinafter referred to as “ Also referred to as “homogeneous liquid crystal”. The liquid crystal molecules 4 are nematic liquid crystals having positive dielectric anisotropy. The twist angle of the liquid crystal molecules 4 is 0 ° or more and 5 ° or less. When a voltage is applied, the liquid crystal molecules 4 tilt in the thickness direction of the liquid crystal layer 3 as shown in FIG. As will be described later, the first polarizer 5 and the second polarizer 6 are arranged in crossed Nicols, and the liquid crystal display panel 10 exhibits a normally white mode.

The phase difference (Δnd) of the liquid crystal display panel 10 is preferably 210 to 310 nm, more preferably 240 to 280 nm, and particularly preferably 260 nm. If Δnd exceeds 310 nm, the drive voltage may increase or the gradation inversion characteristics may deteriorate. If Δnd is less than 210 nm, the luminance may decrease.

The phase difference (residual phase difference) Re in the front direction during black display of the liquid crystal display panel 10 is preferably 40 to 60 nm, more preferably 45 to 55 nm, and particularly preferably 50 nm. When the residual phase difference Re exceeds 60 nm, the viewing angle tends to deteriorate. The relationship between the voltage and the residual phase difference Re is not linear as shown in FIG. 116, and the change in the residual phase difference Re with respect to the change in voltage becomes smaller as the residual phase difference Re becomes smaller. For this reason, if the residual phase difference Re is made too small, specifically, if the residual phase difference Re is less than 40 nm, an adverse effect on power consumption may be increased.

The driving method of the liquid crystal display panel 10 is not particularly limited, and examples thereof include a passive matrix method, an active matrix method, a plasma address method, and the like. In particular, an active matrix system using an active element such as a TFT (Thin Film Transistor) is preferable.

The substrates 1 and 2 align the liquid crystal molecules 4 in a specific direction. Although the substrates 1 and 2 themselves may have the property of aligning the liquid crystal material, usually, an alignment member (for example, an alignment film) having the property of aligning the liquid crystal molecules 4 is respectively provided on the substrates 1 and 2. Provided.

An electrode for applying a voltage to the liquid crystal layer 3 is provided on each of the substrates 1 and 2 on the liquid crystal layer 3 side. Examples of the electrode material include a transparent conductive film such as indium tin oxide (ITO). When a transparent substrate provided with an alignment film is used, the electrode is usually provided between the transparent substrate and the alignment film. A color filter may be provided on the substrate 1 or 2 on the liquid crystal layer 3 side.

The first polarizer 5 and the second polarizer 6 have a function of changing natural light into linearly polarized light. As the 1st polarizer 5 and the 2nd polarizer 6, the normal polarizer used for a liquid crystal display device can be used suitably. A general polarizer is formed by dyeing a substrate, a polyvinyl alcohol (PVA) film, with iodine or a dye and stretching it 4 to 6 times. The first polarizer 5 and the second polarizer 6 are so-called O-type polarizers.

Although the 1st polarizer 5 and / or the 2nd polarizer 6 may be used independently, from a viewpoint of improving intensity | strength, moisture resistance, and heat resistance, as shown in FIG. It is preferable that a transparent protective layer 7 is provided on each of both surfaces of the second polarizer 6. As the transparent protective layer 7, a transparent protective layer used for a general polarizing plate can be appropriately used, and a triacetyl cellulose (TAC) film is usually used. Examples of the TAC film include a TAC film for a liquid crystal polarizing plate manufactured by Konica Minolta Opto and Fujitac manufactured by Fuji Film.

The Rth of a TAC film having a thickness of 40 μm is usually about 30 nm. Therefore, from the viewpoint of using a general TAC film as the transparent protective layer 7, the Rth of the transparent protective layer 7 is preferably 25 to 35 nm, and particularly preferably 30 nm.

On the other hand, a protective film of Rth = 0 nm made of an acrylic polymer may be used as the transparent protective layer 7. Further, as the transparent protective layer provided on the liquid crystal display panel 10 side of the first polarizer 5 and / or the second polarizer 6, the first retardation plate 11, the second retardation plate 12, or the third retardation plate is used instead. May be.

The Rth of the transparent protective layer is preferably zero in the IPS system, but it is better to have Rth in other modes. Accordingly, the Rth of the transparent protective layer 7 is not particularly limited, and can be appropriately set as long as it is within a range satisfying the range of the total Rth.

The second retardation plate 12 is used for optical compensation in the front direction. The retardation value in the thickness direction of the second retardation plate 12 affects the viewing angle characteristic, and the viewing angle characteristic is changed by adjusting the retardation value. The material of the second retardation plate 12 is not particularly limited, and examples thereof include polycarbonate, polysulfone, cellulose acetate, polyvinyl chloride, polyolefin, and the like. The second retardation plate 12 is, for example, a method of uniaxially stretching a polymer film (raw film) made of the above material in the longitudinal (length) or lateral (width) direction, or biaxially in the longitudinal and lateral directions. It can be produced using a method of stretching. The second retardation plate 12 is formed by stretching a polymer film made of the above material in an oblique direction with respect to the vertical or horizontal direction as described in Japanese Patent Application Laid-Open No. 2007-203556 or Japanese Patent Application Laid-Open No. 2007-90532. It may be produced by doing.

The Re of the second retardation plate 12 is particularly preferably 140 nm, but may be 130 to 150 nm (preferably 135 to 145 nm) due to product variations. Re of the second retardation plate 12 is substantially the relationship of (residual retardation Re of the liquid crystal display panel 10) = (Re of the second retardation plate 12) − (retardation Re, h of the liquid crystal film). It is preferable to satisfy

Re = 140 nm retardation plates are produced in large quantities in VA liquid crystal display devices using circularly polarized light and can be used in this embodiment, which is advantageous in terms of cost. In addition, the laminate of Re = 140 nm retardation plate and polarizer also functions as a circularly polarizing plate, so that it is possible to suppress the reflection at the electrodes in the panel from being visually recognized.

The Rth of the second retardation plate 12 is not particularly limited as long as it is set to satisfy the range of the total Rth in consideration of the presence or absence of other optical members such as a third retardation plate and a transparent protective layer.

The Nz coefficient of the second retardation plate 12 is not particularly limited as long as Re and Rth are set to satisfy a desired range.

The third retardation plate is mainly used for adjusting the total Rth. The third retardation plate is optically uniaxial in the thickness direction and satisfies the relationship of nx = ny> nz or nx≈ny> nz. The third retardation plate functions as a so-called negative C plate. It does not specifically limit as a material of a 3rd phase difference plate, For example, the same material as the above-mentioned 2nd phase difference plate 12 is mentioned. A 3rd phase difference plate can be produced using the method of biaxially stretching the polymer film (raw film) which consists of the said material to the vertical and horizontal direction, for example. In addition, a liquid crystalline composition may be used as a material for the third retardation plate. Specifically, for example, a solidified layer or cured layer of a liquid crystalline composition containing a planar aligned liquid crystal compound, a solidified layer or cured layer of a liquid crystalline composition containing a columnar aligned discotic liquid crystal compound, and the like. .

In this specification, “planar alignment” refers to a state in which liquid crystal compounds (liquid crystal molecules) are aligned so that the helical axis of the liquid crystal is perpendicular to the interface between both layers. “Columnar alignment” refers to a state in which discotic liquid crystal compounds are arranged so as to be stacked in a columnar shape. Further, the “solidified layer” refers to a solidified state in which a liquid crystalline composition in a softened, molten or solution state is cooled. Furthermore, the “cured layer” means that a part or all of the liquid crystalline composition is cross-linked by at least one of heat, catalyst, light, and radiation, and is in a stable state of insoluble, insoluble or hardly soluble. The thing that became. In addition, the said hardened layer includes what became the hardened layer via the solidified layer of a liquid crystalline composition.

The “liquid crystalline composition” refers to a liquid crystal phase exhibiting liquid crystallinity. Examples of the liquid crystal phase include a nematic liquid crystal phase, a smectic liquid crystal phase, a cholesteric liquid crystal phase, and a columnar liquid crystal phase. The liquid crystalline composition used for the third retardation plate preferably exhibits a nematic liquid crystal phase. This is because a highly transparent retardation film can be obtained.

The Rth of the third retardation plate is not particularly limited as long as it is set so as to satisfy the range of the total Rth in consideration of the presence or absence of other optical members such as the second retardation plate 12 and the transparent protective layer.

The Nz coefficient of the third retardation plate is not particularly limited as long as Rth is set to satisfy a desired range.

The Rth of a TAC film having a thickness of 40 μm is usually about 30 nm, and this TAC film can be said to be a negative C plate. Thus, you may utilize the above-mentioned transparent protective layer 7 as a 3rd phase difference plate.

The first phase difference plate 11 is a tilted alignment phase difference plate, and is mainly used to improve viewing angle characteristics. The first retardation plate 11 includes at least a liquid crystal film, and the liquid crystal film is made of a liquid crystal material that exhibits optically positive uniaxiality. This material includes at least one nematic liquid crystal exhibiting optically positive uniaxiality. Note that this material may include only the nematic liquid crystal or a composition including the nematic liquid crystal. The liquid crystal film is formed by fixing the nematic liquid crystal in a state of being hybrid-aligned in the normal direction (that is, the thickness direction of the first retardation plate 11) in the liquid crystal state. The first retardation plate 11 may include an overcoat layer made of an acrylic coating material in addition to the liquid crystal film.

In the state in which the nematic liquid crystal is hybrid-aligned, the angle formed by the director of the liquid crystal and the liquid crystal film plane is different between the upper surface and the lower surface of the film. Therefore, the angle formed by the director and the film plane differs between the vicinity of the film upper surface interface and the film lower surface interface, and the angle continuously changes between the upper surface and the lower surface of the film.

In the liquid crystal film, the nematic liquid crystal director is inclined at different angles at all locations in the thickness direction of the film. Therefore, when the liquid crystal film is viewed as a structure called a film, the liquid crystal film has no optical axis.

The liquid crystal film has a specific average tilt angle. The average tilt angle of the liquid crystal film is particularly preferably 37 °, but may be 34 to 40 ° (preferably 35 to 39 °) due to product variation.

In the vicinity of one interface of the liquid crystal film, the angle formed by the director of the nematic liquid crystal and the film plane is usually 20 to 90 ° as an absolute value, preferably 40 to 90 °, and more preferably 50 to 90 °. 80 °. In the interface opposite to the interface, the angle formed is usually 0 to 20 ° as an absolute value, and preferably 0 to 10 °.

In particular, in this embodiment, the angle formed by the director of the nematic liquid crystal and the film plane is 70 ° in the vicinity of one interface of the liquid crystal film, and the angle formed at the interface opposite to the interface is 2 °. In particular, a liquid crystal film in which the angle formed between both interfaces continuously changes is particularly preferable.

The liquid crystal film is arranged so that the interface having the larger absolute value of the angle formed is positioned on the liquid crystal display panel 10 side. In other words, the interface on the side where the nematic liquid crystal stands is arranged closer to the liquid crystal display panel 10 than the interface on the side where the nematic liquid crystal lies.

The material of the liquid crystal film is not particularly limited. For example, the liquid crystal film may be formed by hybrid-aligning a nematic phase low-molecular liquid crystal in a liquid crystal state and then cross-linking and fixing with light, heat, or the like. Specific examples of the liquid crystal film include, for example, an NR film manufactured by Nippon Oil Corporation.

In a film in which nematic liquid crystal is hybrid-aligned, the refractive index ne in the direction parallel to the director of the nematic liquid crystal is different from the refractive index no in the direction perpendicular to the director. Assuming that the value obtained by subtracting no from ne (ne-no) is the apparent birefringence, the in-plane apparent phase difference Re, h when viewed from the normal direction of the liquid crystal film is the apparent birefringence. It is given by the product of (ne-no) and the film thickness of the liquid crystal film.

The phase difference Re, h is preferably 70 to 110 nm, more preferably 80 to 100 nm, and particularly preferably 90 nm. If it exceeds 110 nm, the drive voltage may increase or the gradation inversion characteristics may deteriorate. If it is less than 70 nm, the viewing angle characteristics may deteriorate and the luminance may decrease. The phase differences Re and h can be controlled by changing the thickness of the liquid crystal film. Further, the phase differences Re and h can be easily obtained by using polarization optical measurement such as ellipsometry.

The film thickness of the liquid crystal film is not particularly limited and can be appropriately set according to the physical properties of the material, and is usually 0.2 to 10 μm, preferably 0.3 to 5 μm, more preferably 0.5 to 2 μm. . If the film thickness is less than 0.2 μm, a sufficient compensation effect may not be obtained. If the film thickness exceeds 10 μm, the display on the display device may be unnecessarily colored.

The upper and lower sides of the first retardation plate 11, the orientation direction of the first retardation plate 11, and the orientation direction of the homogeneous liquid crystal of the liquid crystal layer 3 are respectively defined as follows.

The upper and lower sides of the first retardation plate 11 are respectively defined by the angles formed by the director of the nematic liquid crystal and the film plane in the vicinity of the film interface of the liquid crystal film. Specifically, as shown in FIGS. 6 and 7, the surface formed by the director of the nematic liquid crystal 8 and the film plane is 20 to 90 ° on the acute angle side as b-plane, and the angle is 0 on the acute angle side. The surface which is ˜20 ° is defined as c-plane. Also, when the c-plane is viewed from the b-plane through the liquid crystal film, the angle formed by the director of the nematic liquid crystal and the projection component of the director on the c-plane is an acute angle and parallel to the projection component. The direction is defined as the orientation direction 11d of the first retardation plate.

Usually, at the interface of the liquid crystal layer 3, the homogeneous liquid crystal 4 is not parallel to the interface but is tilted at a certain angle, and this angle is generally referred to as a pretilt angle. As shown in FIG. 3, the angle formed by the director of the homogeneous liquid crystal 4 at the interface of the liquid crystal layer 3 and the projection component onto the interface of the director is an acute angle, and the direction parallel to the projection component is homogeneous. This is defined as a liquid crystal alignment direction 4d.

The first retardation plate 11, the second retardation plate 12, the first polarizer 5 and the second polarizer 6 may be bonded to each other via an adhesive layer or a pressure-sensitive adhesive layer. Examples of the adhesive layer or pressure-sensitive adhesive layer material include an acrylic resin. Specific examples include SK-2057 and SK-1478 (heat resistant type) manufactured by Soken Chemical Co., Ltd. In addition, for example, an adhesive layer or pressure-sensitive adhesive layer for whitening due to moisture and heat, a low-adhesive adhesive layer that can be re-peeled, a UV-cut type adhesive layer or pressure-sensitive adhesive layer containing a UV absorber An adhesive layer or pressure-sensitive adhesive layer for an aluminum vapor-deposited surface for preventing peeling of the vapor-deposited surface, a light diffusion type adhesive layer or pressure-sensitive adhesive layer in which light diffusion particles are blended, and the like may be used.

8 to 19 show preferred configurations of the present embodiment. As a suitable structure of this embodiment, the structure by which each member was laminated | stacked in the order shown below is mentioned.

<Configuration 1>
First polarizer 5 / first retardation plate 11 / liquid crystal display panel 10 / second retardation plate 12 / second polarizer 6 (FIG. 8)

<Configuration 1 + transparent protective layer>
First polarizer 5 / transparent protective layer 7 / first retardation plate 11 / liquid crystal display panel 10 / second retardation plate 12 / second polarizer 6 (FIG. 9)

<Configuration 1-1>
First polarizer 5 / first retardation plate 11 / liquid crystal display panel 10 / second retardation plate 12 / third retardation plate 13 / second polarizer 6 (FIG. 10)

<Configuration 1-2>
First polarizer 5 / first retardation plate 11 / liquid crystal display panel 10 / third retardation plate 13 / second retardation plate 12 / second polarizer 6 (FIG. 11)

<Configuration 1-3>
First polarizer 5 / first retardation plate 11 / third retardation plate 13 / liquid crystal display panel 10 / second retardation plate 12 / second polarizer 6 (FIG. 12)

<Configuration 1-4>
First polarizer 5 / third retardation plate 13 / first retardation plate 11 / liquid crystal display panel 10 / second retardation plate 12 / second polarizer 6 (FIG. 13)

<Configuration 2>
First polarizer 5 / second retardation plate 12 / first retardation plate 11 / liquid crystal display panel 10 / second polarizer 6 (FIG. 14)

<Configuration 2 + transparent protective layer>
First polarizer 5 / transparent protective layer 7 / second retardation plate 12 / first retardation plate 11 / liquid crystal display panel 10 / second polarizer 6 (FIG. 15)

<Configuration 2-1>
First polarizer 5 / second retardation plate 12 / first retardation plate 11 / liquid crystal display panel 10 / third retardation plate 13 / second polarizer 6 (FIG. 16)

<Configuration 2-2>
First polarizer 5 / second retardation plate 12 / first retardation plate 11 / third retardation plate 13 / liquid crystal display panel 10 / second polarizer 6 (FIG. 17)

<Configuration 2-3>
First polarizer 5 / second retardation plate 12 / third retardation plate 13 / first retardation plate 11 / liquid crystal display panel 10 / second polarizer 6 (FIG. 18)

<Configuration 2-4>
First polarizer 5 / third retardation plate 13 / second retardation plate 12 / first retardation plate 11 / liquid crystal display panel 10 / second polarizer 6 (FIG. 19)

In each configuration, the first retardation plate 11 is composed only of a liquid crystal film.

Moreover, before and after in each structure, it is not specifically limited. In each configuration, the case where the first polarizer 5 is arranged on the viewer side and the case where the first polarizer 5 is arranged on the backlight side are optically equivalent and show similar display characteristics. Specifically, display characteristics such as gradation inversion characteristics and iso-contrast characteristics are merely rotated by 180 ° about the front direction.

The orientation of the optical axis of each member will be described with reference to FIG. Here, for the sake of convenience, an X axis and a Y axis that are orthogonal to each other are defined in a plane parallel to the main surface of the transparent substrate 1 or 2 constituting the liquid crystal display panel 10. In-plane corresponds to a plane defined by the X-axis and the Y-axis. The X axis corresponds to the horizontal direction of the screen, and the Y axis corresponds to the vertical direction of the screen. Furthermore, the positive (+) direction (0 ° azimuth) of the X axis corresponds to the right side of the screen, and the negative (−) direction (180 ° azimuth) of the X axis corresponds to the left side of the screen. The positive (+) direction (90 ° azimuth) of the Y axis corresponds to the upper side of the screen, and the negative (−) direction (270 ° azimuth) of the Y axis corresponds to the lower side of the screen.

The orientation of the absorption axis 5a of the first polarizer 5 is preferably in the range of 90 ° ± 2 °, more preferably in the range of 90 ° ± 1 °, and particularly preferably 90 °. If it is out of the range of 90 ° ± 2 °, the contrast may be lowered.

The orientation of the absorption axis 6a of the second polarizer 6 is preferably in the range of 0 ° ± 2 °, more preferably in the range of 0 ° ± 1 °, and particularly preferably 0 °. If it is out of the range of 0 ° ± 2 °, the contrast may be lowered.

The orientation of the slow axis 12a of the second retardation plate 12 is preferably in the range of 135 ° ± 2 °, more preferably in the range of 135 ° ± 1 °, and particularly preferably 135 °. If it is out of the range of 135 ° ± 2 °, the contrast may be lowered.

The orientation direction 4d of the homogeneous liquid crystal is preferably in the range of 45 ° ± 2 °, more preferably in the range of 45 ° ± 1 °, and particularly preferably 45 °. If it is out of the range of 45 ° ± 2 °, the contrast may be lowered.

The orientation direction 11d of the first retardation plate 11 is preferably in the range of 225 ° ± 2 °, more preferably in the range of 225 ° ± 1 °, and particularly preferably 225 °. If it is out of the range of 225 ° ± 2 °, the contrast may be lowered.

Note that the orientations of these optical axes are not absolute, and the relative angles between the optical axes need only be within the above-described range. That is, the absorption axis 5a and the absorption axis 6a are preferably orthogonal to each other. Specifically, the angle formed by the absorption axis 5a and the absorption axis 6a is preferably in the range of 90 ° ± 2 °, more preferably. Is in the range of 90 ° ± 1 °, particularly preferably 90 °. When the azimuth that bisects the angle formed by the absorption axis 5a and the absorption axis 6a is φ1, the direction of the slow axis 12a is preferably in the range of φ1 ± 2 °, more preferably in the range of φ1 ± 1 °. And particularly preferably φ1. The orientation direction 4d of the homogeneous liquid crystal and the orientation direction 11d of the first retardation plate are preferably opposite to each other and parallel to each other. Specifically, they are opposite to each other, and to each other. It is preferable that the angle formed by the direction is in the range of 0 ° ± 2 ° (more preferably in the range of 0 ° ± 1 °, particularly preferably 0 °).

The results of simulating isocontrast characteristics and gradation inversion characteristics by changing the total Rth for each configuration are shown below. Note that in the gradation inversion characteristics, a region where the gradation is reversed (a region where seven gradations are darker than the zero gradation) is shown in dark gray, and a region where the gradation is not reversed (seven gradations are brighter than the zero gradation). Region) is shown in light gray. In the diagram of isocontrast characteristics, the innermost contour line shows a contrast ratio of 50: 1.

The simulation conditions are as shown below, and an LCD master manufactured by Shintech Co. was used for the simulation.
Liquid crystal display panel phase difference (Δnd): 260 nm
・ Residual phase difference Re of liquid crystal display panel: 50 nm
-Re of second retardation plate: 140 nm
-Re of third retardation plate: 0 nm
-Average tilt angle of liquid crystal film: 37 °
・ Phase difference Re, h of liquid crystal film: 90 nm
-Rth of transparent protective layer: 30 nm
-Re of transparent protective layer: 0nm
-Absorption axis of the first polarizer: 90 °
-Absorption axis of the second polarizer: 0 °
-Slow axis of the second retardation plate: 135 °
-Orientation direction of homogeneous liquid crystal: 45 °
-Orientation direction of the first retardation plate: 225 °
・ White display: 0V

When visual evaluation of gradation inversion on an actual panel was performed, gradation inversion was particularly effectively suppressed when the gradation inversion occupancy was improved by 20% compared to the reference value of total Rth. It was visible. The reference value of total Rth was 70 nm. This is because the most preferable Re (= 140 nm) of the second retardation plate 12 and the Nz coefficient (= 1) expressed when the original film of the second retardation plate 12 is longitudinally uniaxially stretched, which is the simplest method. ) And determined from. Therefore, in the following evaluation, when only the most general Rth of the second retardation plate 12 is considered as the total Rth in each configuration, that is, when the total Rth = 70 nm, 1. Twice was used as the criterion value. If it is above this criterion value, very good gradation inversion characteristics can be realized. However, for the configuration 1 + transparent protective layer and the configuration 2 + transparent protective layer, since the Rth of the transparent protective layer is fixed at 30 nm, the configuration excluding the transparent protective layer, that is, the determination reference value in the configuration 1 or 2 Based on. Further, in configurations 1-1 to 1-4 and configurations 2-1 to 2-4, the criterion is 1.2 times the non-grayscale inversion occupancy when the Rth of the third retardation plate is 0 nm. Value.

Note that when the non-gradation inversion occupancy is improved by 13% compared to the total Rth = 70 nm, it can be visually recognized that the gradation inversion is suppressed, and the non-gradation inversion is less than when the total Rth = 70 nm. When the occupancy rate was improved by 15%, it was visually recognized that gradation inversion was suppressed, although not as much as when it was improved by 20%.

For the isocontrast characteristics, the viewing angle occupancy at the reference value of total Rth (= 70 nm) was used as the determination reference value. If it is above this reference value, the isocontrast characteristic is not sacrificed even if the gradation inversion characteristic is improved.

For configurations 1 and 2, the second retardation plate 12 is set by setting the Nz coefficient of the second retardation plate 12 to 1, 1.4, 1.6, 1.8, 2, 2.3, or 2.6. FIGS. 21 to 28 show the calculation results when Rth of 12 is set to 70 nm, 126 nm, 154 nm, 182 nm, 210 nm, 252 nm, or 294 nm. In addition, FIG. 29 and Table 1 show the results of calculating the non-gradation inversion occupancy for configurations 1 and 2. In configurations 1 and 2, the Rth of the second retardation plate 12 is the total Rth as it is.

As a result, it has been found that the configuration 1 exhibits a non-gradation inversion occupancy ratio equal to or higher than the determination reference value in the range where the total Rth is 120 nm or more and 300 nm or less, and can realize very excellent gradation inversion characteristics. In Configuration 1, the total Rth may be 180 nm or more, or 250 nm or more. As a result, the gradation inversion characteristics can be greatly improved. Further, in the configuration 2, it was found that the non-gradation inversion occupancy ratio equal to or higher than the determination reference value was exhibited in the range where the total Rth was 120 nm or more and 260 nm or less, and very excellent gradation inversion characteristics could be realized. In Configuration 2, the total Rth may be 180 nm or more. Thereby, the gradation inversion characteristic can be greatly improved.

For the configuration 1 + transparent protective layer and the configuration 2 + transparent protective layer, the Nz coefficient of the second retardation plate 12 is set to 1, 1.4, 1.6, 1.8, 2, 2.3, or 2.6. 30 to 37 show the results calculated by setting the Rth of the second retardation plate 12 to 70 nm, 126 nm, 154 nm, 182 nm, 210 nm, 252 nm, or 294 nm. In addition, FIG. 38 and Table 2 show the results of calculating the non-gradation inversion occupancy ratio for the configuration 1 + transparent protective layer and the configuration 2 + transparent protective layer. In the configuration 1 + transparent protective layer and the configuration 2 + transparent protective layer, the total Rth is the sum of each Rth of the second retardation plate 12 and Rth (30 nm) of the transparent protective layer.

As a result, it was found that in the configuration 1 + transparent protective layer, the total Rth showed a non-gradation inversion occupancy ratio equal to or higher than the criterion value in the range of 150 nm or more and 330 nm or less, and very excellent gradation inversion characteristics could be realized. In the configuration 1 + transparent protective layer, the total Rth may be 210 nm or more. Thereby, the gradation inversion characteristic can be greatly improved. In addition, it was found that the configuration 2 + transparent protective layer exhibits a non-gradation inversion occupancy ratio equal to or higher than a criterion value in a range where the total Rth is 150 nm or more and 240 nm or less, and can realize very excellent gradation inversion characteristics.

For configurations 1-1 to 1-4, the Nz coefficient of the second retardation plate 12 is fixed to 1, the Rth of the second retardation plate 12 is fixed to 70 nm, and the Rth of the third retardation plate is set to 0 nm, 60 nm, 70 nm, FIGS. 39 to 62 show the results calculated by setting to 80 nm, 90 nm, 100 nm, 120 nm, 140 nm, 160 nm, 180 nm, 200 nm, or 220 nm. In addition, FIGS. 63 to 67 and Table 3 show the results of calculating the non-gradation inversion occupancy and the viewing angle occupancy for configurations 1-1 to 1-4. In the configurations 1-1 to 1-4, the total Rth is the sum of Rth (70 nm) of the second retardation plate 12 and each Rth of the third retardation plate.

As a result, in the configuration 1-1, when the total Rth is in the range of 140 nm or more and 250 nm or less, the non-gradation inversion non-occupancy exceeding the determination reference value is exhibited without sacrificing the viewing angle occupancy, and the isocontrast characteristics are obtained. It was found that very good gradation inversion characteristics can be realized without deteriorating. From the same viewpoint, it was found that in the configuration 1-2, the total Rth is preferably in the range of 130 nm or more and 290 nm or less. In Configuration 1-3, it was found that the total Rth is preferably in the range of 130 nm to 290 nm. Moreover, in the structure 1-4, it turned out that the range whose total Rth is 140 nm or more and 250 nm or less is preferable. Further, in configurations 1-2 and 1-3, the total Rth may be 170 nm or more. Thereby, the gradation inversion characteristic can be greatly improved.

For configurations 2-1 to 2-4, the Nz coefficient of the second retardation plate 12 is fixed to 1, the Rth of the second retardation plate 12 is fixed to 70 nm, and the Rth of the third retardation plate is set to 0 nm, 60 nm, 70 nm, 68 to 91 show the calculation results obtained by setting to 80 nm, 90 nm, 100 nm, 120 nm, 140 nm, 160 nm, 180 nm, 200 nm, or 220 nm. In addition, FIGS. 92 to 96 and Table 4 show the results of calculating the non-gradation inversion occupancy and the viewing angle occupancy for configurations 2-1 to 2-4. In configurations 2-1 to 2-4, the total Rth is the sum of Rth (70 nm) of the second retardation plate 12 and each Rth of the third retardation plate.

As a result, in the configuration 2-1, the total Rth is in the range of 140 nm or more and 250 nm or less, and the non-gradation inversion non-occupancy exceeding the determination reference value is exhibited without sacrificing the viewing angle occupancy, and the isocontrast characteristics are obtained. It was found that very good gradation inversion characteristics can be realized without deteriorating. From the same viewpoint, it was found that in the configuration 1-2, the total Rth is preferably in the range of 140 nm or more and 210 nm or less. In Configuration 1-3, it was found that the total Rth is preferably in the range of 130 nm to 210 nm. Moreover, in the structure 1-4, it turned out that the range whose total Rth is 140 nm or more and 270 nm or less is preferable. In Configuration 2-1, the total Rth may be 170 nm or more, or 230 nm or more. In the configurations 2-2 and 2-4, the total Rth may be 170 nm or more. As a result, the gradation inversion characteristics can be greatly improved.

97 and Table 5 collectively show the results of Configuration 1, Configuration 1 + transparent protective layer, and Configurations 1-1 to 1-4.

As a result, if the total Rth is in the range of 150 nm or more and 250 nm or less, in any of the configuration 1, the configuration 1 + transparent protective layer, and the configurations 1-1 to 1-4, the non-gradation that is equal to or higher than the determination reference value. It was found to show a reversal occupancy. That is, in the form in which the first polarizer 5 / first retardation plate 11 / liquid crystal display panel 10 / second retardation plate 12 / second polarizer 6 are laminated in this order, the total Rth is 150 nm or more and 250 nm or less. It was found that by setting the range, very excellent gradation inversion characteristics can be realized with certainty.

FIG. 98 and Table 6 collectively show the results of Configuration 2, Configuration 2 + transparent protective layer, and Configurations 2-1 to 2-4.

As a result, if the total Rth is in the range of 150 nm or more and 210 nm or less, in any of the configuration 2, the configuration 2 + transparent protective layer, and the configurations 2-1 to 2-4, a non-gradation that is equal to or higher than the criterion value It was found to show a reversal occupancy. That is, in the form in which the first polarizer 5 / second retardation plate 12 / first retardation plate 11 / liquid crystal display panel 10 / second polarizer 6 are laminated in this order, the total Rth is 150 nm or more and 210 nm or less. It was found that by setting the range, very excellent gradation inversion characteristics can be realized with certainty.

Next, examples of the liquid crystal display device according to the first embodiment will be described. In each of the following embodiments, the direction of the slow axis of each phase difference plate and the direction of the absorption axis of the polarizer are defined by an angle formed with the X axis as shown in FIG.

Example 1
In the liquid crystal display device of Example 1, as shown in FIG. 99, a transparent protective layer 7 made of a TAC film, a first polarizer 5, a transparent protective layer 7 made of a TAC film, and a first retardation plate 11 made of a liquid crystal film. The liquid crystal display panel 10, the second retardation plate 12, the second polarizer 6, and the transparent protective layer 7 made of the TAC film were provided in this order from the backlight side. Thus, Example 1 is an example regarding the structure of the above-mentioned structure 1 + transparent protective layer.

The transparent protective layer 7 and the first retardation plate 11 were bonded together via an acrylic adhesive layer 14 having a thickness of 5 μm. Moreover, the 1st phase difference plate 11 and the liquid crystal display panel 10 were bonded together through the acrylic adhesive layer 14 with a thickness of 25 micrometers. Further, the liquid crystal display panel 10 and the second retardation plate 12 were bonded together via an acrylic adhesive layer 14 having a thickness of 20 μm.

In the liquid crystal display panel 10, the liquid crystal layer is composed of a liquid crystal composition containing homogeneously aligned liquid crystal molecules, and a liquid crystal material (Δn = 0.65) manufactured by Merck Ltd. was applied as the liquid crystal composition. At this time, the director of the homogeneous liquid crystal (major axis direction of the liquid crystal molecules) was regulated by the rubbing direction of the alignment film, and the alignment direction of the homogeneous liquid crystal was set to 45 °. The pretilt angle of the homogeneous liquid crystal was set to 3 °. The gap (cell gap) in the liquid crystal layer was set to 4 μm. At the time of black display, the residual phase difference Re of the liquid crystal display panel 10 was 50 nm.

In order to compensate for the birefringence caused by the homogeneous liquid crystal, the orientation direction of the first retardation plate 11 was set to an orientation (225 ° orientation) substantially antiparallel to the rubbing direction so as to have a sequential compensation relationship. The phase difference Re, h of the liquid crystal film was set to 90 nm. The average tilt angle of the liquid crystal film was set to 37 °, and the film thickness (including the overcoat layer) of the liquid crystal film was 7 μm. As such a first retardation plate 11, an NH film manufactured by Nippon Oil Corporation was applied.

The slow axis of the second retardation plate 12 was set to an orientation (135 ° orientation) substantially perpendicular to the orientation direction of the homogeneous liquid crystal and the first retardation plate 11. The Re of the second retardation plate 12 was set to 140 nm so as to correspond to the sum of the residual retardation Re of the liquid crystal display panel 10 and the retardations Re and h of the liquid crystal film. Further, the Nz coefficient of the second retardation plate 12 was set to 1.6. As a result, the Rth of the second retardation plate 12 was 154 nm. The film thickness of the second retardation plate 12 was 32 μm. As such a second retardation plate 12, ZEONOR manufactured by Optes Co., Ltd. was applied.

In order to convert the linearly polarized light that has passed through the first polarizer 5 into desired elliptically polarized light or linearly polarized light and enter the liquid crystal layer, the absorption axis of the first polarizer 5 depends on the orientation direction of the first retardation plate 11 and The azimuth (90 ° azimuth) was set so as to intersect the slow axis of the second retardation plate 12 at about 45 °. On the other hand, the absorption axis of the second polarizer 6 was set to an orientation (0 ° orientation) that is substantially orthogonal to the absorption axis of the first polarizer 5. The film thicknesses of the first polarizer 5 and the second polarizer 6 were each 28 μm. As such 1st polarizer 5 and 2nd polarizer 6, the PVA film made from a Kuraray company was dyed with iodine, and the polarizing film produced by extending | stretching was applied.

The film thickness of the TAC film was 40 μm, and the Rth of the TAC film was 30 nm. As such a TAC film, a TAC film for a liquid crystal polarizing plate manufactured by Konica Minolta Opto Co., Ltd. was applied.

The total Rth in the liquid crystal display device of Example 1 was the sum of Rth (30 nm) of the transparent protective layer 7 and Rth (154 nm) of the second retardation plate 12, and was approximately 184 nm.

(Example 2)
Similar to the liquid crystal display device of Example 1 except that the Nz coefficient of the second retardation plate 12 is set to 1.4, the Rth of the second retardation plate 12 is set to 126 nm, and the total Rth is changed to 156 nm. Thus, a liquid crystal display device of Example 2 was produced.

(Example 3)
Similar to the liquid crystal display device of Example 1, except that the Nz coefficient of the second retardation plate 12 is set to 1.8, the Rth of the second retardation plate 12 is set to 182 nm, and the total Rth is changed to 212 nm. Thus, a liquid crystal display device of Example 3 was produced.

(Example 4)
In the liquid crystal display device of Example 4, as shown in FIG. 100, a transparent protective layer 7 made of a TAC film, a first polarizer 5, a second retardation plate 12, a first retardation plate 11 made of a liquid crystal film, and a liquid crystal The display panel 10, the transparent protective layer 7 made of a TAC film, the second polarizer 6 and the transparent protective layer 7 made of a TAC film were provided in this order from the backlight side. Thus, Example 4 and Example 1 differ only in the arrangement relationship of each member. Example 4 is an example relating to the configuration of the above-described configuration 2 + the transparent protective layer.

In addition, the 2nd phase difference plate 12 and the 1st phase difference plate 11 were bonded together through the acrylic adhesive layer 14 with a thickness of 5 micrometers. Moreover, the 1st phase difference plate 11 and the liquid crystal display panel 10 were bonded together through the acrylic adhesive layer 14 with a thickness of 25 micrometers. Moreover, the liquid crystal display panel 10 and the transparent protective layer 7 were bonded together via the acrylic adhesive layer 14 with a thickness of 20 μm.

(Example 5)
Similar to the liquid crystal display device of Example 4 except that the Nz coefficient of the second retardation plate 12 is set to 1.4, the Rth of the second retardation plate 12 is set to 126 nm, and the total Rth is changed to 156 nm. Thus, a liquid crystal display device of Example 5 was produced.

(Example 6)
Similar to the liquid crystal display device of Example 4 except that the Nz coefficient of the second retardation plate 12 is set to 1.8, the Rth of the second retardation plate 12 is set to 182 nm, and the total Rth is changed to 212 nm. Thus, a liquid crystal display device of Example 6 was produced.

(Comparative Example 1)
Except that the Nz coefficient of the second retardation plate 12 was set to 1, the Rth of the second retardation plate 12 was set to 70 nm, and the total Rth was changed to 100 nm, the same as in the liquid crystal display device of Example 4. A liquid crystal display device of Comparative Example 1 was produced.

Using the results of actually measuring the gradation inversion characteristics of the liquid crystal display devices of Examples 1 to 6 and Comparative Example 1 and the conditions for manufacturing the liquid crystal display devices of Examples 1 to 6 and Comparative Example 1, The simulation results were compared. The simulation is the same as the simulation result of the above-described configuration 1 + transparent protective layer or configuration 2 + transparent protective layer. The results are shown in FIG.

As is clear from FIG. 101 and Table 7, the difference between the actually measured value and the value obtained by the simulation is within about 3%, and the actual non-gradation inversion occupancy can be evaluated with high accuracy using the simulation. I understand.

Next, the presence / absence of a correlation between the gradation inversion characteristic and the isocontrast characteristic will be described.
102 and 103 show isocontrast characteristics and gradation inversion characteristics of a TN liquid crystal display device provided with a wide view film (WV film). 104 to 111 show isocontrast characteristics and gradation inversion characteristics of an ECB liquid crystal display device. 112 and 113 show isocontrast characteristics and gradation inversion characteristics of an ASV (Advanced Super View) type liquid crystal display device which is an embodiment of the VA system. In the ASV method, when a voltage is applied, liquid crystal molecules are tilted in all directions like fireworks.

104 and 105 includes a polarizing plate, a retardation plate (Re = 270 nm), a liquid crystal film (retardation Re, h = 90 nm), an ECB liquid crystal display panel, a retardation plate (Re = 270 nm, Nz coefficient = 1.4), a retardation plate (Re = 270 nm), and a polarizing plate are provided in this order from the backlight side.

106 and 107 include a polarizing plate, a retardation plate (Re = 270 nm), a liquid crystal film (retardation Re, h = 90 nm), an ECB liquid crystal display panel, a retardation plate (Re = 270 nm, Nz coefficient = 1.0), a retardation plate (Re = 270 nm), and a polarizing plate are provided in this order from the backlight side.

108 and 109 show the evaluation results of the liquid crystal display device having the above-described configuration 2, and FIGS. 110 and 111 show the evaluation results of the liquid crystal display device having the above-described configuration 1. FIG.

From these figures, it can be seen that there is no correlation between the gradation inversion characteristics and the iso-contrast characteristics. That is, when the liquid crystal mode is different, the aspect of both characteristics changes greatly. Further, there is a difference in gradation inversion characteristics between ECB type liquid crystal display devices. For example, comparing the liquid crystal display device of FIGS. 104 and 105 with the liquid crystal display device of FIGS. 106 and 107, the liquid crystal display device of FIGS. The properties are clearly bad. Thus, just because the isocontrast characteristics are good, it cannot be said that the gradation inversion characteristics are good.

As shown in FIG. 114, when a voltage is applied to the ECB liquid crystal display panel, the phase difference changes in accordance with the gradation voltage in the front direction (polar angle 0 °). However, since the rugby ball-like liquid crystal molecules rise in the oblique direction, the tilt angle of the head portion (inflection point) of the rugby ball changes depending on the voltage, and the phase difference does not change according to the gradation voltage. The phenomenon occurs. If only the viewing angle of the iso-contrast characteristic is widened, a system that can compensate only 63 gradations and 0 gradations may be used. However, improving gradation reversal means that this reversed part is improved. Yes, you need to do something different. If there is no reverse part, gradation inversion does not occur. In the VA system such as the ASV system, the liquid crystal molecules are regulated so that the head part (inflection point part) of the liquid crystal molecules is tilted in all directions. Therefore, when the picture elements are viewed on average, the inflection point portion of each liquid crystal molecule is canceled by the inflection point portion of the other liquid crystal molecules, and it can be considered that the inflection point portion has disappeared. In the IPS system, the liquid crystal molecules are aligned so that the inflection point is not visible from the display surface. On the other hand, in the TN method and the ECB method, an inflection point portion inevitably appears, so that gradation inversion is likely to occur.

According to the present invention, a liquid crystal display device suitable for the ECB method in which gradation inversion easily occurs can be realized.

(Embodiment 2)
Hereinafter, the liquid crystal display device of Embodiment 2 will be described. In addition, about the member which overlaps in Embodiment 2 and Embodiment 1, description is abbreviate | omitted and the same code | symbol was attached | subjected.

The liquid crystal display device of this embodiment is a transmissive liquid crystal display device. As shown in FIG. 115, the transparent protective layer 7 made of a TAC film, the first polarizer 5, the transparent protective layer 7 made of a TAC film, and the liquid crystal A first retardation plate 11 made of a film, a liquid crystal display panel 10, a second retardation plate 212, a second polarizer 6 and a transparent protective layer 7 made of a TAC film are provided in this order from the backlight side.

In the present embodiment, a TAC film having a thickness of 40 μm is used as the transparent protective layer 7. The Rth of the TAC film is particularly preferably 30 nm, but may be 25 to 35 nm due to product variations. On the other hand, a protective film of Rth = 0 nm made of an acrylic polymer may be used as the transparent protective layer 7.

As a laminated body of the transparent protective layer 7, the first polarizer 5 and the transparent protective layer 7, a general polarizing plate can be used.

The second retardation plate 212 is used for optical compensation in the front direction. The retardation value in the thickness direction of the second retardation plate 212 affects the viewing angle characteristic, and the viewing angle characteristic is changed by adjusting the retardation value. The second retardation plate 212 is manufactured using the same material and method as the second retardation plate 12 of the first embodiment.

The Re of the second retardation plate 212 is particularly preferably 140 nm, but may be 130 to 150 nm (preferably 135 to 145 nm) due to product variations. Further, Re of the second retardation plate 212 is substantially the relationship of (residual retardation Re of the liquid crystal display panel 10) = (Re of the second retardation plate 212) − (retardation of liquid crystal film Re, h). It is preferable to satisfy

Re = 140 nm retardation plates are produced in large quantities in VA liquid crystal display devices using circularly polarized light and can be used in this embodiment, which is advantageous in terms of cost. In addition, the laminate of Re = 140 nm retardation plate and polarizer also functions as a circularly polarizing plate, so that it is possible to suppress the reflection at the electrodes in the panel from being visually recognized.

As described above, a general circularly polarizing plate can be suitably used as the laminate of the second retardation plate 212, the second polarizer 6, and the transparent protective layer 7.

The Nz coefficient of the second retardation plate 212 is particularly preferably 1.55, but may be 1.35 to 1.75 (preferably 1.4 to 1.7) depending on product variations.

The Rth of the second retardation plate 212 that satisfies the above Re and Nz coefficients is particularly preferably 147 nm, but it may be 140 to 155 nm depending on product variations. In the present embodiment, the total Rth is the sum of Rth of the second retardation plate 212 and Rth (30 nm) of the transparent protective layer 7 and is 120 nm or more.

The laminated body (polarizing plate) of the transparent protective layer 7, the first polarizer 5 and the transparent protective layer 7, and the first retardation plate 11 are an adhesive layer or an adhesive layer (for example, an acrylic adhesive having a thickness of 5 μm). Layer). Moreover, the 1st phase difference plate 11 and the liquid crystal display panel 10 are bonded together through the adhesive bond layer or the adhesive layer (for example, 25-micrometer-thick acrylic adhesive layer). Further, the liquid crystal display panel 10 and the laminate (circular polarizing plate) of the second retardation plate 212, the second polarizer 6 and the transparent protective layer 7 are an adhesive layer or an adhesive layer (for example, an acrylic layer having a thickness of 25 μm). Pasted via a pressure-sensitive adhesive layer). In addition, you may use what was illustrated in Embodiment 1 as an adhesive bond layer and an adhesive layer.

In the second embodiment, the azimuth and orientation direction of the optical axis of each member is set in the same manner as in the first embodiment.

As described above, according to the present embodiment, similar to the first embodiment, it is possible to exhibit excellent gradation inversion characteristics when displaying near black.

Specifically, the non-gradation inversion occupation ratio of the liquid crystal display device of Embodiment 2 is preferably 60% or more. If the non-gradation inversion occupancy is less than 60%, it may be felt that gradation inversion is not sufficiently suppressed when the vicinity of black is displayed.

This application claims the priority based on the Paris Convention or the laws and regulations in the country of transition based on Japanese Patent Application No. 2009-207543 filed on Sep. 8, 2009. The contents of the application are hereby incorporated by reference in their entirety.

1, 2: Transparent substrate 3: Liquid crystal layer 4: Homogeneous liquid crystal 4d: Orientation direction of homogeneous liquid crystal 5: First polarizer 5a: Absorption axis 6 of first polarizer 6: Second polarizer 6a: Absorption of second polarizer Axis 7: Transparent protective layer 8: Nematic liquid crystal 10: Liquid crystal display panel 11: First retardation plate 11d: Orientation direction of first retardation plate 12: Second retardation plate 12a: Slow axis of second retardation plate 13: Third retardation plate 14: Adhesive layer

Claims (5)

A liquid crystal display device comprising a first polarizer, a second polarizer, a liquid crystal display panel, a first retardation plate and a second retardation plate,
The second polarizer is disposed opposite to the first polarizer,
The liquid crystal display panel is provided between the first polarizer and the second polarizer,
The first retardation plate and the second retardation plate are provided independently of each other between the first polarizer or the second polarizer and the liquid crystal display panel,
The liquid crystal display panel has a pair of substrates disposed to face each other, and a liquid crystal layer sandwiched between the pair of substrates,
The liquid crystal layer includes homogeneously aligned liquid crystal molecules,
The first retardation plate includes a liquid crystal film,
The liquid crystal film is formed by fixing a nematic liquid crystal in a state of hybrid alignment,
The phase difference of the liquid crystal display panel is 210 nm or more and 310 nm or less,
The in-plane apparent retardation of the liquid crystal film when viewed from the normal direction of the liquid crystal film is 70 nm or more and 110 nm or less,
The in-plane retardation of the second retardation plate is 130 nm or more and 150 nm or less,
In a plane parallel to the main surfaces of the pair of substrates, when a certain direction is a 0 ° azimuth,
The orientation of the absorption axis of the first polarizer is in the range of 90 ° ± 2 °,
The orientation of the absorption axis of the second polarizer is in the range of 0 ° ± 2 °,
The orientation of the slow axis of the second retardation plate is in the range of 135 ± 2 °,
The orientation direction of the homogeneously oriented liquid crystal molecules is in the range of 45 ° ± 2 °,
The orientation direction of the first retardation plate is in the range of 225 ± 2 °,
The liquid crystal display device further includes a third retardation plate that is optically uniaxial in the thickness direction,
The first polarizer, the first retardation plate, the liquid crystal display panel, the second retardation plate, the third retardation plate, and the second polarizer are arranged in this order,
The specific retardation, which is the retardation in the thickness direction of the member between the first polarizer and the second polarizer, excluding the liquid crystal layer and the first retardation plate, is 140 nm or more and 250 nm or less. liquid crystal display device characterized. A liquid crystal display device comprising a first polarizer, a second polarizer, a liquid crystal display panel, a first retardation plate and a second retardation plate,
The second polarizer is disposed opposite to the first polarizer,
The liquid crystal display panel is provided between the first polarizer and the second polarizer,
The first retardation plate and the second retardation plate are provided independently of each other between the first polarizer or the second polarizer and the liquid crystal display panel,
The liquid crystal display panel has a pair of substrates disposed to face each other, and a liquid crystal layer sandwiched between the pair of substrates,
The liquid crystal layer includes homogeneously aligned liquid crystal molecules,
The first retardation plate includes a liquid crystal film,
The liquid crystal film is formed by fixing a nematic liquid crystal in a state of hybrid alignment,
The phase difference of the liquid crystal display panel is 210 nm or more and 310 nm or less,
The in-plane apparent retardation of the liquid crystal film when viewed from the normal direction of the liquid crystal film is 70 nm or more and 110 nm or less,
The in-plane retardation of the second retardation plate is 130 nm or more and 150 nm or less,
In a plane parallel to the main surfaces of the pair of substrates, when a certain direction is a 0 ° azimuth,
The orientation of the absorption axis of the first polarizer is in the range of 90 ° ± 2 °,
The orientation of the absorption axis of the second polarizer is in the range of 0 ° ± 2 °,
The orientation of the slow axis of the second retardation plate is in the range of 135 ± 2 °,
The orientation direction of the homogeneously oriented liquid crystal molecules is in the range of 45 ° ± 2 °,
The orientation direction of the first retardation plate is in the range of 225 ± 2 °,
The liquid crystal display device further includes a third retardation plate that is optically uniaxial in the thickness direction,
The first polarizer, the third retardation plate, the first retardation plate, the liquid crystal display panel, the second retardation plate, and the second polarizer are arranged in this order,
The specific retardation, which is the retardation in the thickness direction of the member between the first polarizer and the second polarizer, excluding the liquid crystal layer and the first retardation plate, is 140 nm or more and 250 nm or less. liquid crystal display device characterized. A liquid crystal display device comprising a first polarizer, a second polarizer, a liquid crystal display panel, a first retardation plate and a second retardation plate,
The second polarizer is disposed opposite to the first polarizer,
The liquid crystal display panel is provided between the first polarizer and the second polarizer,
The first retardation plate and the second retardation plate are provided independently of each other between the first polarizer or the second polarizer and the liquid crystal display panel,
The liquid crystal display panel has a pair of substrates disposed to face each other, and a liquid crystal layer sandwiched between the pair of substrates,
The liquid crystal layer includes homogeneously aligned liquid crystal molecules,
The first retardation plate includes a liquid crystal film,
The liquid crystal film is formed by fixing a nematic liquid crystal in a state of hybrid alignment,
The phase difference of the liquid crystal display panel is 210 nm or more and 310 nm or less,
The in-plane apparent retardation of the liquid crystal film when viewed from the normal direction of the liquid crystal film is 70 nm or more and 110 nm or less,
The in-plane retardation of the second retardation plate is 130 nm or more and 150 nm or less,
In a plane parallel to the main surfaces of the pair of substrates, when a certain direction is a 0 ° azimuth,
The orientation of the absorption axis of the first polarizer is in the range of 90 ° ± 2 °,
The orientation of the absorption axis of the second polarizer is in the range of 0 ° ± 2 °,
The orientation of the slow axis of the second retardation plate is in the range of 135 ± 2 °,
The orientation direction of the homogeneously oriented liquid crystal molecules is in the range of 45 ° ± 2 °,
The orientation direction of the first retardation plate is in the range of 225 ± 2 °,
The liquid crystal display device further includes a third retardation plate that is optically uniaxial in the thickness direction,
The first polarizer, the second retardation plate, the third retardation plate, the first retardation plate, the liquid crystal display panel, and the second polarizer are arranged in this order,
The specific retardation, which is a retardation in the thickness direction of a member between the first polarizer and the second polarizer, excluding the liquid crystal layer and the first retardation plate, is 130 nm or more and 210 nm or less. liquid crystal display device characterized. A liquid crystal display device comprising a first polarizer, a second polarizer, a liquid crystal display panel, a first retardation plate and a second retardation plate,
The second polarizer is disposed opposite to the first polarizer,
The liquid crystal display panel is provided between the first polarizer and the second polarizer,
The first retardation plate and the second retardation plate are provided independently of each other between the first polarizer or the second polarizer and the liquid crystal display panel,
The liquid crystal display panel has a pair of substrates disposed to face each other, and a liquid crystal layer sandwiched between the pair of substrates,
The liquid crystal layer includes homogeneously aligned liquid crystal molecules,
The first retardation plate includes a liquid crystal film,
The liquid crystal film is formed by fixing a nematic liquid crystal in a state of hybrid alignment,
The phase difference of the liquid crystal display panel is 210 nm or more and 310 nm or less,
The in-plane apparent retardation of the liquid crystal film when viewed from the normal direction of the liquid crystal film is 70 nm or more and 110 nm or less,
The in-plane retardation of the second retardation plate is 130 nm or more and 150 nm or less,
In a plane parallel to the main surfaces of the pair of substrates, when a certain direction is a 0 ° azimuth,
The orientation of the absorption axis of the first polarizer is in the range of 90 ° ± 2 °,
The orientation of the absorption axis of the second polarizer is in the range of 0 ° ± 2 °,
The orientation of the slow axis of the second retardation plate is in the range of 135 ± 2 °,
The orientation direction of the homogeneously oriented liquid crystal molecules is in the range of 45 ° ± 2 °,
The orientation direction of the first retardation plate is in the range of 225 ± 2 °,
The liquid crystal display device further includes a third retardation plate that is optically uniaxial in the thickness direction,
The first polarizer, the third retardation plate, the second retardation plate, the first retardation plate, the liquid crystal display panel, and the second polarizer are arranged in this order,
The specific retardation, which is a retardation in the thickness direction of a member between the first polarizer and the second polarizer, excluding the liquid crystal layer and the first retardation plate, is 140 nm or more and 270 nm or less. liquid crystal display device characterized. The non gray scale inversion occupancy of the liquid crystal display device, a liquid crystal display device according to any one of claims 1 to 4, characterized in that 60% or more.

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